1. Field of the Invention
This invention relates to stable thickened alkali metal hypochlorite bleaching compositions. More particularly, this invention is concerned with thickened compositions of alkali metal hypochlorites suitable as a clogged drain opening composition, or for other bleaching applications, which compositions, in terms of viscosity and hypochlorite content, are stable for many months and even years.
2. Discussion of the Prior Art
Aqueous solutions of alkali metal hypochlorite bleaching agents are widely used in the bleaching of textile materials, as well as in general purpose cleaning and bleaching of hard surfaces, including dishes, glasses, metal surfaces, pots, pans, and the like. In addition, in view of the capability of the bleaching agents to attack protein fibers such as hair and food particles, which are often the cause of clogged drains in bathroom and kitchen sinks, aqueous compositions containing alkali metal hypochlorite are used as liquid drain opening compositions, usually in combination with alkali metal hydroxide. Such a composition is disclosed in U.S. Pat. No. 3,697,431 to Summerfelt.
Summerfelt teaches that wetting agents, or surface active agents, in amounts of from 0.25% to up to about 1% by weight, may be utilized to increase the rate at which the drain opener penetrates the fatty substance which clogs the drain. In amounts in excess of 1%, deterioration of the hypochlorite is accelerated. Anionic monophosphate esters of an ethoxylated alcohol or the salts of a perfluoroacid are the only hypochlorite and hydroxide compatible wetting agents mentioned.
U.S. Pat. No. 4,116,850 to Ruck discloses drain opener compositions which are aqueous solutions of a soluble metallic hydroxide, a chlorine releasing agent, and a catalyst which is a metallic chloride of a Group VI metal.
There is no suggestion of adding any thickening agents in either the Summerfelt or Ruck patents. However, thickened alkali metal hypochlorite bleaching and cleaning compositions have been suggested in view of the advantage of thickened compositions in bleaching and/or cleaning vertical surfaces. The use of various types of clays and/or polymeric or cellulosic thickeners in aqueous alkali metal hypochlorite compositions is described in the following U.S. Pat. No.: 3,558,496--Zmoda (mixture of positively charged clay and negatively charged clay); U.S. Pat. No. 3,843,548--James (paste or gel for medicinal or veterinary purposes--using synthetic magnesium silicate clay); U.S. Pat. Nos. 3,985,668 and 4,005,027--Hartman (false body, fluid abrasive scouring composition--using clays as colloid-forming thickening agents); U.S. Pat. No. 4,011,172--Marsan, et al (for automatic clothes dryer--using colloidal silicas, polyacrylamides, cellulose derivatives, e.g. carboxymethylcellulose, or clays of various types, e.g. smectite and Laponite); U.S. Pat. No. 4,071,463--Steinhauer (Laponite clay-example 5); U.S. Pat. No. 4,116,849--Leikhim and U.S. Pat. No. 4,116,851--Rupe, et al (natural or synthetic clay, colloidal silica, particulate polymers, carboxypolymethylene); U.S. Pat. No. 4,147,650--Sabatelli et al (slurried detergent--sodium tripolyphosphate and sodium polyacrylate); U.S. Pat. No. 4,235,732--Beyer (clay-as suspending and false-body agent).
The use of various detergents or surface-active agents for providing a thickening function in alkali metal hypochlorite bleach containing compositions has also been suggested. For example, mention can be made of the following U.S. Pat. No.: 3,684,722--Hynam, et al (mixtures of C.sub.8 --C.sub.13 alkali-metal soaps with amine oxides or long chain substituted betaines); U.S. Pat. Nos. 3,956,158, 4,154,694 and 4,155,871--Donaldson (combination of 3-dimensional network of entangled filaments of insoluble material, including fatty acid soaps, e.g. sodium stearate, with a mixture of detergent-active compounds, i.e. a mixture of alkali metal C.sub.12 to C.sub.18 alkyl sulphates with trialkyl amine oxide, trialkyl phosphine oxide or dialkyl sulphoxide detergent-active materials); U.S. Pat. No. 4,229,313--Joy (branched chain amine oxides of formula R--CH(R.sub.1)--CH.sub.2 --NR.sub.2 R.sub.3 .fwdarw.O); U.S. Pat. No. 4,271,030--Brierly, et al (detergent micellar complexes); U.S. Pat. No. 4,282,109--Citrone, et al (blend of amine oxide and alkali metal alkyl sulfate).
Also, British Pat. No. 1,466,560, which is referred to in the Brierly, et al and Citrone, et al U.S. patents, discloses a thickened aqueous alkali metal hypochlorite composition in which thickening is imparted by an admixture of certain sarcosinate or tauride surfactants, in an amount of 0.1 to 5% by weight, with one or more of the surfactants: soaps, certain quaternary ammonium compounds, amine oxides, betaines and alkanolamides, in an amount of from 0.1 to 5% by weight. Stability at room temperature for several weeks is observed.
However, there is still a need for thickened aqueous alkali metal hypochlorite compositions of improved stability both with regard to the hypochlorite concentration and the viscosity of the composition, as well as with respect to phase stability, i.e. there should not be any phase separation of the composition during storage, even over extended periods.
A major difficulty in finding suitable organic thickeners lies in the interaction between thickeners and hypochlorites. Because of this interaction, both viscosity and hypochlorite concentration decrease as a function of time. The rate of hypochlorite degradation that occurs as a result of the interaction with the thickener is typically much faster than the reduction in hypochlorite concentration taking place in commercial hypochlorite solutions according to the equation: EQU NaOCl.fwdarw.NaCl+1/2O.sub.2 .uparw..
In many instances the compositions split into two phases. Moreover, many conventional thickeners are simply ineffective when used in aqueous hypochlorite compositions.
The problem of compatibility and stability between many classes or organic surface-active compounds and hypochlorite and the ineffectiveness of many conventional thickeners is well recognized and is discussed in several of the above mentioned patents. For example, Hynam, et al U.S. Pat. No. 3,684,722 teaches the ineffectiveness of various polymeric thickeners, Veegum T, celluloses, silicones, water glass, bentonite, liquid paraffin, and sodium stearate (soap); Hartman, U.S. Pat. Nos. 3,985,668 and 4,005,027 teaches that alkyl benzene sulfonates, olefin sulfonates, alkyl glyceryl ether sulfonates, alkyl ether sulfates and ethoxylated nonionic surfactants are to be avoided, while bleach stable surfactants that are especially resistant to hypochlorite oxidation fall into two main groups: water-soluble alkyl sulfates containing from about 8 to 18 carbon atoms in the alkyl group and water-soluble betaine surfactants.
U.S. Pat. No. 3,560,389 to Hunting discloses a liquid detergent bleach composition containing alkali metal hypochlorite, a bleach compatible detergent and a hydrotrope as a means of providing a clear, stable formulation which does not lose its oxidizing and/or detergent powers. Four suitable classes of detergents are described, including alkali metal sulfates, e.g. sodium lauryl sulfate; alkali metal ether sulfates, e.g. sodium lauryl ether sulfate; alkali metal alkylaryl sulfonate, e.g. sodium dodecyl benzene sulfonate; and oxidation products of fatty amines, i.e. amine oxides. It is also indicated that mixtures of these detergents may be used, although mixtures with other unnamed detergents may not be compatible. Hunting does not mention any thickening being provided by these detergents nor are any ranges of proportions given for mixtures of detergents.
It has now been found that even among the classes of surfactants described in these patents as being compatible with and providing stable compositions with alkali metal hypochlorites generally only a few of the many surfactants in each class are in fact stable enough for commercial applications. Although the reason for this "selectivity" of stability within specific classes or types of surfactant materials has not been fully understood, it is hypothesized that the presence of impurities in the commercially available materials, e.g. trace heavy metals (Co, Ni, Cu), alcohols, --NH--compounds, oxidizable organic compounds, etc. may be one cause for breakdown in the hypochlorite either by reaction or by catalysis.
Further extensive experiments and research to find hypochlorite compatible surfactants and especially surfactant mixtures revealed that only certain combinations of surfactant compounds and then only in certain critical proportions were capable of providing stable thickened hypochlorite bleaching compositions.
Moreover, it has now been discovered that for one intended utility of the thickened alkali metal hypochlorite compositions, namely, for unclogging clogged drains, improvement in flow rates requires a relatively narrow range of viscosity.
Accordingly, it is an object of the invention to provide stable thickened alkali metal hypochlorite compositions.
It is another object of the invention to provide a mixture of readily available anionic surface active compounds which can be used to increase the viscosity of alkali metal hypochlorite compositions.
It is still another object of the invention to provide a thickened alkali metal hypochlorite composition for unclogging clogged drains which is not expensive to produce and which remains stable for extended periods of time with regard to both product viscosity and hypochlorite ion concentration, as well as to phase stability.
A still further object of the invention is to provide a cleaning and bleaching composition which has a viscosity especially effective for unclogging clogged drains with P-type traps.